Monday, November 14, 2011

Mod Your Moxon For Half Laps

Schwarz's Tongue

If you have a Moxon vise, whether it be with Benchcrafted hardware, or the wood screw version, or the F-clamp version, or the pipe-clamp version, or the T-nut and donut version, etc. you'll want to follow Chris Schwarz's lead and cut a big fat chamfer on the front of your chop. This gives you clearance for tilting your saw down (or is it up?) for cutting half-lap dovetails. The vise will work without it, but in our opinion the chamfer looks nice, especially with the lamb's tongue, and thats reason enough to add it. In case you were wondering, it does not weaken the vise, or make you crank down on the wheels to hold your work.

If you're like me, when you see a lamb's tongue and wonder how to do it, you think about how to cut that flowing curve smoothly. Well, that's really the easy part. It's the chamfer you don't think about, since it seems straightforward. But since its stopped it creates some problems. You cant simply tilt your plane and have at it. Chris has his own method, which he illustrates in this Lee Valley Newsletter. But its for a smaller chamfer. Cutting one of this size calls for some heavier work.

Here's how I did it. When I tested the idea last week I cut the chamfer by sawing a series of saw kerfs about 5/8" apart, across the corner of the chop, stopping just short of my layout lines. I then broke these pieces off with a chisel to get rid of most the waste. I followed up with a drawknife to clean up the remnants of the saw kerfs and to smooth the chamfer. In dry, hard maple this is tough work. Then I refined the chamfer with a rabbeting block plane, working across the grain (up the hill) to get the chamfer flat. Finally I drawfiled the flat and finished up with a card scraper. The lambs tongue (mine is slightly different, below) I shaped with drawknife and scraper, followed by a few swipes of 220 going downhill.

Those boards in the vise are part of my Jefferson Bookcases in beech that I started last week. The Moxon vise has been indispensable for this project.